"Fifteen years! It's amazing, isn't it?" Pinkett Smith told PEOPLE at the New York City premiere of Madagascar 3: Europe's Most Wanted recently.
"I was just doing the Today show, and there was a couple there who was celebrating 59 years of marriage, and I thought to myself, '15 years ain't nothing, you know?' It's just the beginning. That's the way I look at it."
So how will they mark the milestone? "You know, we celebrate throughout the year," she added to PEOPLE at Friday's MOMS Mamarazzi event in New York. "But usually on our wedding anniversary, we give ourselves a high-five and go, 'We survived another year, homie! Yeah!' "
The actress, 40, compares marriage to "a beautiful journey with lots of chapters."
"You know, we are nothing like what we were when we first met. Nothing like that," she said. "Biggest change is that we have grown up. We have matured."
Becoming 'Best of Friends'Under the spotlight, their marriage has endured plenty of speculation, and Pinkett Smith called recent rumors of marital trouble "ridiculous."
Criticism aside, they're "the best of friends," she said. "We as men and women have to learn how to be friends with one another. It's not just about loving someone. It's about understanding, acceptance and compassion."
She added: "You have to be there for each other. That's how you build great relationships."
The family-oriented star, who plays Gloria the Hippo in the animated Dreamworks film, said she was happy that her husband and their children – Jaden, 13, and Willow, 11 – came to the Madagascar premiere. "That's the whole point of having family," she said.
Not that she expected any less. Says Pinkett Smith: "Tell me what that's going to look like at home if he doesn't come to something as important as this!"